Numerous films are provided with decorative indicia by an embossing process in which the film is passed between a pressure roll and an embossing roll to receive such decorative indicia. These films may be formed of numerous polymeric materials including, for example, polyolefins, linear polyesters, polyamides and, for example, poly(vinyl chloride). Additionally these films may optionally be provided with a suitable backing such as, for example, a reinforcing mesh backing of either glass fibers or polymeric fibers such as poly(ethylene terephthlate). The backing may be of the woven or the non-woven type. The methods of manufacturing such films are well known in the art. One specific field where such embossed films are produced is in the manufacture of wallcoverings.
There is a need in the art to provide a process for manufacturing embossing rolls in a more economical manner. There is also a need in the art for manufacturing rolls which are capable of providing embossed, more aesthetically pleasing ornamentation on films without the occurrence of seams. Additionally, in providing a process for manufacturing embossing rolls, there is a need to inject the skilled artist into the manufacturing process to provide the decorative indicia for the rolls, and thereby, provide the opportunity for the innovative creation of a wide variety of ornamental patterns and designs.
Presently, one technique for manufacturing embossing rolls is an electroforming process in which a segmented sleeve is formed. This segmented sleeve provides for the occurrence of seams which is aesthetically undesirable. This is also an expensive and time consuming process and it removes the artist from the process of forming the embossing cylinder.
U.S. Pat. No. 4,634,484 is directed to embossing rollers and forms a sleeve which is positioned around a core and used as the embossing medium. This sleeve is made by a time consuming multi-step process which is costly. In accordance with this process, a design on a roller is coated with a silicone rubber to form an annular member having indicia disposed internally. This sleeve is then turned inside-out and used as an embossing medium to emboss the external surface of a tube of thermoplastic film. The tube of embossed thermoplastic film is then in turn coated with a silicone rubber to form another annular or cylindrical sleeve member which is then vulcanized and turned inside-out. After being turned inside-out the sleeve is drawn over a core roller, after the core roller has been coated with an adhesion promoter and a silicone adhesive, the adhesive coating is then hardened and the composite roller is used as an embossing roller in a device for the continuous embossing of a thermoplastic rectilinear film. Obviously, this is a labor and capital intensive process. Moreover, since the embossing roll is a composite, as opposed to a unitary roll in which the embossing indicia is integral and unitary with the external surface of roll, there is a danger of slippage of the sleeve along the underlying surface which can seriously adversely impact production quality and efficiency.
No molding of the decorating cylinder is suggested by U.S. Pat. No. 4634484.
U.S. Pat. No. 4,551,297 also discloses the formation of a composite embossing or decorating cylinder which includes a silicone sleeve member bearing indicia to be embossed onto a film and wherein the sleeve is adhered to the surface of a cylindrical core. This patent does not describe the formation, by molding, of an embossing cylinder within a sleeve.
Both of the above specific patents are essentially directed at duplicating a leather grain and are not concerned with providing a method wherein the artists may exercise their innovative talents of creating original patterns on a seamless cylinder for use in the continuous embossing of films.
The present invention satisfies the above needs in the art by providing for a process in which seamless embossing rolls are formed in a highly economical manner and in a short period of time. The embossing rolls formed by this invention are unitary; that is, the embossing indicia is integral with the surface of the rolls and is not on a separate sleeve member requiring an additional process step of adhesively adhering the sleeve member to a supporting surface. Furthermore, the present process integrates the artist into the embossing roll production process. The artist can now provide a variety of artistic and original decorative indicia into the rolls which, in turn, will be embossed on the film.